Imprint lithography

ABSTRACT

An imprinting method is disclosed that, in embodiment, includes contacting first and second spaced target regions of an imprintable medium on a substrate with first and second templates respectively to form respective first and second imprints in the medium and separating the first and second templates from the imprinted medium.

This application is a continuation of co-pending U.S. patent applicationSer. No. 12/615,505, filed Nov. 10, 2009, now allowed, which is acontinuation of U.S. patent application Ser. No. 11/303,026, filed Dec.16, 2005, now U.S. Pat. No. 7,636,475, which is a continuation-in-partapplication of U.S. patent application Ser. No. 11/019,521, filed Dec.23, 2004, now U.S. Pat. No. 7,676,088, the content of each of theforegoing applications is herein incorporated in its entirety byreference.

FIELD

The present invention relates to imprint lithography.

BACKGROUND

A lithographic apparatus is a machine that applies a desired patternonto a target portion of a substrate. Lithographic apparatus areconventionally used, for example, in the manufacture of integratedcircuits (ICs), flat panel displays and other devices involving finestructures.

It is desirable to reduce the size of features in a lithographic patternbecause this allows for a greater density of features on a givensubstrate area. In photolithography, the increased resolution may beachieved by using radiation of a short wavelength. However, there areproblems associated with such reductions. Lithographic apparatus using193 nm wavelength radiation are starting to be adopted but even at thislevel, diffraction limitations may become a barrier. At lowerwavelengths, the transparency of projection system materials is poor.Thus, optical lithography capable of enhanced resolution will likelyrequire complex optics and rare materials and thus will be expensive.

An alternative method to printing sub-100 nm features, known as imprintlithography, comprises transferring a pattern to a substrate byimprinting a pattern into an imprintable medium using a physical mouldor template. The imprintable medium may be the substrate or a materialcoated onto a surface of the substrate. The imprintable medium may befunctional or may be used as a “mask” to transfer a pattern to anunderlying surface. The imprintable medium may, for instance, beprovided as a resist deposited on a substrate, such as a semiconductormaterial, to which the pattern defined by the template is to betransferred. Imprint lithography is thus essentially a moulding processon a micrometer or nanometer scale in which the topography of a templatedefines the patterns created on a substrate. Patterns may be layered aswith optical lithography processes so that in principle imprintlithography could be used for such applications as integrated circuitmanufacture.

The resolution of imprint lithography is limited only by the resolutionof the template fabrication process. For instance, imprint lithographyhas been used to produce features in the sub-50 nm range with goodresolution and line edge roughness. In addition, imprint processes maynot require the expensive optics, advanced illumination sources orspecialized resist materials typically required for optical lithographyprocesses.

SUMMARY

According to a first aspect of the invention, there is provided animprinting method, comprising providing first and second spaced targetregions of a substrate with imprintable medium, contacting the first andsecond spaced target regions with first and second templatesrespectively to form respective first and second imprints in the medium,separating the first and second templates from the imprinted medium,providing third and fourth spaced target regions of the substrate withimprintable medium, displacing the first template in a first directionfrom the first region to a third region of the medium and displacing thesecond template in a second direction from the second region to a fourthregion of the medium, and contacting the third and fourth target regionswith the first and second templates respectively to form respectivethird and fourth imprints in the medium. In an embodiment, separatefirst, second, third and fourth volumes of the imprintable medium may beprovided on the substrate to provide the spaced target regions of themedium.

In this way, it may possible to imprint a significant area of thesubstrate in a short time, which may improve the throughput of animprint lithography system. Each template may be used to imprint aplurality of spaced regions of the imprintable medium.

The first direction may take any desirable orientation in relation tothe second direction. For example, the first direction may be angularlyoffset from the second direction by any appropriate angle to enable thevarious regions of the imprintable medium to be imprinted in the optimalmanner for a given imprint system. In an embodiment, the first directionis substantially parallel to the second direction.

In an embodiment, the first and second templates contact the mediumsimultaneously, alternatively, the first and second templates maycontact the medium sequentially. When contacting the mediumsequentially, the timing between each sequential contacting step may bemonitored and/or controlled to provide an optimum process to imprint aparticular substrate with a particular pattern.

According to an aspect of the invention, there is provided a method forpatterning a substrate, comprising:

contacting first and second spaced target regions of an imprintablemedium on a substrate with first and second templates respectively toform respective first and second imprints in the medium, each imprintcomprising a pattern feature and an area of reduced thickness;

separating the first and second templates from the imprinted medium;

etching the area of reduced thickness in the first and second targetregions to expose predefined areas of the substrate; and

etching the exposed predefined areas of the substrate.

Since multiple templates are employed, the rate at which a substrate ispatterned may be increased relative to conventional methods employing asingle template.

In an embodiment, the method comprises, after separating the templatesfrom the imprinted medium and before etching the areas of reducedthickness, displacing the first template in a first direction from thefirst region to a third region of the medium and displacing the secondtemplate in a second direction from the second region to a fourth regionof the medium, and contacting the third and fourth target regions withthe first and second templates respectively to form respective third andfourth imprints in the medium, each imprint comprising a pattern featureand an area of reduced thickness.

According to an aspect of the invention, there is provided an imprintingapparatus, comprising a substrate table configured to hold a substrate,a template support configured to support first and second templates, thetemplate support configured to cause the first and second templates tocontact first and second spaced target regions respectively of animprintable medium on the substrate to form respective first and secondimprints in the medium and to cause the first and second templates toseparate from the imprinted medium, and a first dispenser configured toprovide a first volume of the imprintable medium and a second dispenserconfigured to provide a second volume of the imprintable medium, toprovide the first and second spaced target regions.

In this way, the imprinting apparatus may imprint a significant area ofthe substrate in a short time, which may improve the throughput of animprint lithography system.

In an embodiment, the template support is operable such that, afterseparating the first and second templates from the first and secondregions of the imprinted medium, the first template is displaced in afirst direction from the first region to a third region of the mediumand the second template is displaced in a second direction from thesecond region to a fourth region of the medium, and the template supportis operable to cause the third and fourth target regions to be contactedwith the first and second templates respectively to form respectivethird and fourth imprints in the medium.

In an embodiment, the first and second dispensers are associated withthe first and second templates respectively. The first and seconddispensers may be fixed relative to the first and second templatesrespectively, or may be moveable independently of the first and secondtemplates.

In an embodiment, the first and second dispensers are provided with aplurality of apertures. The plurality of apertures may comprise atwo-dimensional array of apertures. Alternatively, the plurality ofapertures may comprise a single row of apertures. Dispensers may beassociated with two or more sides of the templates.

The apparatus and method of the present invention may be suitable forapplication in a drop on demand process (e.g., step and flash imprintlithography—SFIL). Accordingly, in an embodiment, the method and/orapparatus may be provided to enable this process.

Appropriately, one or more dispensers may be configured to provideseparate third and fourth volumes of an imprintable medium on asubstrate to provide the third and fourth spaced target regions.

While the first direction may take any desirable orientation in relationto the second direction, in an embodiment, the first direction issubstantially parallel to the second direction.

The template support may be operable so that the first and secondtemplates contact the first and second regions of the mediumsimultaneously, alternatively, the template support may be operable sothat the first and second templates contact the first and second regionsof the medium sequentially.

Appropriately, the template support may be configured so that the firsttemplate is fixed relative to the second template. Alternatively, thetemplate support may be configured so that the first template ismoveable relative to the second template.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying schematic drawings in whichcorresponding reference symbols indicate corresponding parts, and inwhich:

FIG. 1 a-1 c illustrate examples of conventional soft, hot and UVlithography process respectively;

FIG. 2 illustrates a two step etching process employed when hot and UVimprint lithography is used to pattern a resist layer;

FIG. 3 illustrates relative dimensions of template features compared tothe thickness of a typical imprintable resist layer deposited on asubstrate;

FIG. 4 illustrates a multi-stamp printing arrangement in accordance withan embodiment of the present invention;

FIG. 5 illustrates a multi-stamp printing arrangement in accordance withan embodiment of the present invention in which the imprintable mediumis provided by drop on demand;

FIG. 6 illustrates a further multi-stamp printing arrangement inaccordance with an embodiment of the present invention in which theimprintable medium is provided by drop on demand; and

FIG. 7 illustrates a further multi-stamp printing arrangement inaccordance with an embodiment of the present invention in which theimprintable medium is provided by drop on demand.

DETAILED DESCRIPTION

There are two principal approaches to imprint lithography which will betermed generally as hot imprint lithography and UV imprint lithography.There is also a third type of “printing” lithography known as softlithography. Examples of these are illustrated in FIGS. 1 a to 1 c.

FIG. 1 a schematically depicts the soft lithography process whichinvolves transferring a layer of molecules 11 (typically an ink such asa thiol) from a flexible template 10 (typically fabricated frompolydimethylsiloxane (PDMS)) onto a resist layer 13 which is supportedupon a substrate 12 and planarization and transfer layer 12′. Thetemplate 10 has a pattern of features on its surface, the molecularlayer being disposed upon the features. When the template is pressedagainst the resist layer, the layer of molecules 11 stick to the resist.Upon removal of the template from the resist, the layer of molecules 11stick to the resist, the residual layer of resist is etched such thatthe areas of the resist not covered by the transferred molecular layerare etched down to the substrate.

The template used in soft lithography may be easily deformed and maytherefore not be suited to high resolution applications, e.g. on ananometer scale, since the deformation of the template may adverselyaffect the imprinted pattern. Furthermore, when fabricating multiplelayer structures, in which the same region will be overlaid multipletimes, soft imprint lithography may not provide overlay accuracy on ananometer scale.

Hot imprint lithography (or hot embossing) is also known as nanoimprintlithography (NIL) when used on a nanometer scale. The process uses aharder template made from, for example, silicon or nickel, which aremore resistant to wear and deformation. This is described for instancein U.S. Pat. No. 6,482,742 and illustrated in FIG. 1 b. In a typical hotimprint process, a solid template 14 is imprinted into a thermosettingor a thermoplastic polymer resin 15, which has been cast on the surfaceof substrate. The resin may, for instance, be spin coated and baked ontothe substrate surface or more typically (as in the example illustrated)onto a planarization and transfer layer 12′. It should be understoodthat the term “hard” when describing an imprint template includesmaterials which may generally be considered between “hard” and “soft”materials, such as for example “hard” rubber. The suitability of aparticular material for use as an imprint template is determined by itsapplication requirements.

When a thermosetting polymer resin is used, the resin is heated to atemperature such that, upon contact with the template, the resin issufficiently flowable to flow into the pattern features defined on thetemplate. The temperature of the resin is then increased to thermallycure (e.g. crosslink) the resin so that it solidifies and irreversiblyadopts the desired pattern. The template may then be removed and thepatterned resin cooled.

Examples of thermoplastic polymer resins used in hot imprint lithographyprocesses are poly(methyl methacrylate), polystyrene, poly(benzylmethacrylate) or poly(cyclohexyl methacrylate). The thermoplastic resinis heated so that it is in a freely flowable state immediately prior toimprinting with the template. It is typically necessary to heatthermoplastic resin to a temperature considerably above the glasstransition temperature of the resin. The template is pressed into theflowable resin and sufficient pressure is applied to ensure the resinflows into all the pattern features defined on the template. The resinis then cooled to below its glass transition temperature with thetemplate in place whereupon the resin irreversibly adopts the desiredpattern. The pattern will consist of the features in relief from aresidual layer of the resin which may then be removed by an appropriateetch process to leave only the pattern features.

Upon removal of the template from the solidified resin, a two-stepetching process is typically performed as illustrated in FIGS. 2 a to 2c. The substrate 20 has a planarization and transfer layer 21immediately upon it, as shown in FIG. 2 a. The purpose of theplanarization and transfer layer is twofold. It acts to provide asurface substantially parallel to that of the template, which helpsensure that the contact between the template and the resin is parallel,and also to improve the aspect ratio of the printed features, as will bedescribed below.

After the template has been removed, a residual layer 22 of thesolidified resin is left on the planarization and transfer layer 21,shaped in the desired pattern. The first etch is isotropic and removesparts of the residual layer 22, resulting in a poor aspect ratio offeatures where L1 is the height of the features 23, as shown in FIG. 2b. The second etch is anisotropic (or selective) and improves the aspectratio. The anisotropic etch removes those parts of the planarization andtransfer layer 21 which are not covered by the solidified resin,increasing the aspect ratio of the features 23 to (L2/D), as shown inFIG. 2 c. The resulting polymer thickness contrast left on the substrateafter etching can be used as for instance a mask for dry etching if theimprinted polymer is sufficiently resistant, for instance as a step in alift-off process.

Hot imprint lithography suffers from a disadvantage in that not onlymust the pattern transfer be performed at a higher temperature, but alsorelatively large temperature differentials might be required in order toensure the resin is adequately solidified before the template isremoved. Temperature differentials between 35 and 100° C. may be needed.Differential thermal expansion between, for instance, the substrate andtemplate may then lead to distortion in the transferred pattern. Thismay be exacerbated by the relatively high pressure required for theimprinting step, due the viscous nature of the imprintable material,which can induce mechanical deformation in the substrate, againdistorting the pattern.

UV imprint lithography, on the other hand, does not involve such hightemperatures and temperature changes nor does it require such viscousimprintable materials. Rather, UV imprint lithography involves the useof a partially or wholly transparent template and a UV-curable liquid,typically a monomer such as an acrylate or methacrylatee. In general,any photopolymerisable material could be used, such as a mixture ofmonomers and an initiator. The curable liquid may also, for instance,include a dimethyl siloxane derivative. Such materials are less viscousthan the thermosetting and thermoplastic resins used in hot imprintlithography and consequently move much faster to fill template patternfeatures. Low temperature and low pressure operation also favors higherthroughput capabilities.

An example of a UV imprint process is illustrated in FIG. 1 c. A quartztemplate 16 is applied to a UV curable resin 17 in a similar manner tothe process of FIG. 1 b. Instead of raising the temperature as in hotembossing employing thermosetting resins, or temperature cycling whenusing thermoplastic resins, UV radiation is applied to the resin throughthe quartz template in order to polymerise and thus cure it. Uponremoval of the template, the remaining steps of etching the residuallayer of resist are the same or similar as for the hot embossing processdescribed above. The UV curable resins typically used have a much lowerviscosity than typical thermoplastic resins so that lower imprintpressures can be used. Reduced physical deformation due to the lowerpressures, together with reduced deformation due to high temperaturesand temperature changes, makes UV imprint lithography suited toapplications requiring high overlay accuracy. In addition, thetransparent nature of UV imprint templates can accommodate opticalalignment techniques simultaneously to the imprinting.

Although this type of imprint lithography mainly uses UV curablematerials, and is thus generically referred to as UV imprintlithography, other wavelengths of radiation may be used to cureappropriately selected materials (e.g. activate a polymerisation orcross linking reaction). In general, any radiation capable of initiatingsuch a chemical reaction may be used if an appropriate imprintablematerial is available. Alternative “activating radiation” may, forinstance, include visible light, infrared radiation, x-ray radiation andelectron beam radiation. In the general description above, and below,references to UV imprint lithography and use of UV radiation are notintended to exclude these and other activating radiation possibilities.

As an alternative to imprint systems using a planar template which ismaintained substantially parallel to the substrate surface, rollerimprint systems have been developed. Both hot and UV roller imprintsystems have been proposed in which the template is formed on a rollerbut otherwise the imprint process is very similar to imprinting using aplanar template. Unless the context requires otherwise, references to animprint template include references to a roller template.

There is a particular development of UV imprint technology known as stepand flash imprint lithography (SFIL) which may be used to pattern asubstrate in small steps in a similar manner to optical steppersconventionally used in IC manufacture. This involves printing smallareas of the substrate at a time by imprinting a template into a UVcurable resin, ‘flashing’ UV radiation through the template to cure theresin beneath the template, removing the template, stepping to anadjacent region of the substrate and repeating the operation. The smallfield size of such step and repeat processes may help reduce patterndistortions and CD variations so that SFIL may be particularly suited tomanufacture of IC and other devices requiring high overlay accuracy.

Although in principle the UV curable resin can be applied to the entiresubstrate surface, for instance by spin coating, this may be problematicdue to the volatile nature of UV curable resins.

One approach to addressing this problem is the so-called ‘drop ondemand’ process in which the resin is dispensed onto a target portion ofthe substrate in droplets immediately prior to imprinting with thetemplate. The liquid dispensing is controlled so that a predeterminedvolume of liquid is deposited on a particular target portion of thesubstrate. The liquid may be dispensed in a variety of patterns and thecombination of carefully controlling liquid volume and placement of thepattern can be employed to confine patterning to the target area.

Dispensing the resin on demand as mentioned is not a trivial matter. Thesize and spacing of the droplets are carefully controlled to ensurethere is sufficient resin to fill template features while at the sametime minimizing excess resin which can be rolled to an undesirably thickor uneven residual layer since as soon as neighboring drops touch theresin will have nowhere to flow.

Although reference is made above to depositing UV curable liquids onto asubstrate, the liquids could also be deposited on the template and ingeneral the same techniques and considerations will apply.

FIG. 3 illustrates the relative dimensions of the template, imprintablematerial (curable monomer, thermosetting resin, thermoplastic, etc.),and substrate. The ratio of the width of the substrate, D, to thethickness of the curable resin layer, t, is of the order of 10⁶. It willbe appreciated that, in order to avoid the features projecting from thetemplate damaging the substrate, the dimension t should be greater thanthe depth of the projecting features on the template.

The residual layer of imprintable material left after stamping is usefulin protecting the underlying substrate, but may also impact obtaininghigh resolution and/or overlay accuracy. The first ‘breakthrough’ etchis isotropic (non-selective) and will thus to some extent erode thefeatures imprinted as well as the residual layer. This may beexacerbated if the residual layer is overly thick and/or uneven.

This etching may, for instance, lead to a variation in the thickness offeatures ultimately formed on the underlying substrate (i.e. variationin the critical dimension). The uniformity of the thickness of a featurethat is etched in the transfer layer in the second anisotropic etch isdependant upon the aspect ratio and integrity of the shape of thefeature left in the resin. If the residual resin layer is uneven, thenthe non-selective first etch may leave some of these features with“rounded” tops so that they are not sufficiently well defined to ensuregood uniformity of feature thickness in the second and any subsequentetch process.

In principle, the above problem may be reduced by ensuring the residuallayer is as thin as possible but this may require application ofundesirably large pressures (possibly increasing substrate deformation)and relatively long imprinting times (perhaps reducing throughput).

As noted above, the resolution of the features on the template surfaceis a limiting factor on the attainable resolution of features printed onthe substrate. The templates used for hot and UV imprint lithography aregenerally formed in a two-stage process. Initially, the required patternis written using, for example, electron beam writing to give a highresolution pattern in resist. The resist pattern is then transferredinto a thin layer of chrome which forms the mask for the final,anisotropic etch step to transfer the pattern into the base material ofthe template. Other techniques such as for example ion-beam lithography,X-ray lithography, extreme UV lithography, epitaxial growth, thin filmdeposition, chemical etching, plasma etching, ion etching or ion millingcould be used. Generally, a technique capable of very high resolutionwill be desired as the template is effectively a 1× mask with theresolution of the transferred pattern being limited by the resolution ofthe pattern on the template.

The release characteristics of the template are also a consideration.The template may, for instance, be treated with a surface treatmentmaterial to form a thin release layer on the template having a lowsurface energy (a thin release layer may also be deposited on thesubstrate).

Another consideration in the development of imprint lithography is themechanical durability of the template. The template may be subjected tolarge forces during stamping of the imprintable medium, and in the caseof hot imprint lithography, it may also be subjected to high pressureand temperature. The force, pressure and/or temperature may causewearing of the template, and may adversely affect the shape of thepattern imprinted upon the substrate.

In hot imprint lithography, a potential advantage may be realized inusing a template of the same or similar material to the substrate to bepatterned in order to help reduce differential thermal expansion betweenthe two. In UV imprint lithography, the template is at least partiallytransparent to the activation radiation and accordingly quartz templatesare used.

Although specific reference may be made in this text to the use ofimprint lithography in the manufacture of ICs, it should be understoodthat imprint apparatus and methods described may have otherapplications, such as the manufacture of integrated optical systems,guidance and detection patterns for magnetic domain memories, hard diskmagnetic media, flat panel displays, thin-film magnetic heads, etc.

While in the description above particular reference has been made to theuse of imprint lithography to transfer a template pattern to a substratevia an imprintable resin effectively acting as a resist, in somecircumstances the imprintable material may itself be a functionalmaterial, for instance having a functionally such as conductivity,optical linear or non linear response, etc. For example, the functionalmaterial may form a conductive layer, a semiconductive layer, adielectric layer or a layer having another desirable mechanical,electrical or optical property. Some organic substances may also beappropriate functional materials. Such applications may be within thescope of one or more embodiments of the present invention.

An imprint lithography system may offer an advantage over opticallithography in terms of reduced feature width. However, the time takento stamp and cure the resin at each location on the substrate may limitthe throughput of an imprint lithography system and therefore a possibleeconomic advantage of adopting imprint lithography.

An embodiment of the present invention involves using a plurality oftemplates located on the same imprinting apparatus operating in parallelto each other, rather than using a single template on the apparatus.

FIG. 4 illustrates a substrate 40 substantially covered with animprintable medium. First and second templates 41, 42 are moved paralleland adjacent one another to imprint a pattern defined by the templates41, 42 respectively into the imprintable medium, which can then bereplicated in the substrate by one or more rounds of etching to removeresidual layers of imprintable medium remaining between pattern featuresafter imprinting and then etch exposed areas of the substrate underlyingthe residual layers.

In an embodiment, the templates are fixed relative to one another suchthat they always print regions having a fixed spatial separation.According to an alternative embodiment, the templates are free to moverelative to one another in order to better or optimally cover the areaof the surface to be printed. A refinement of this embodiment involvesat least one template having a smaller area than the other (or others).In such a system, the larger template(s) can imprint the main area ofthe substrate while the smaller template(s) can move around the edges ofthe printing area or between the gaps between the printed areas left bythe larger template(s).

The above embodiments may lend themselves for particular application todrop on demand processes (e.g., SFIL) in which the imprintable medium isapplied to the substrate as required, rather than being dispensed acrossthe entirety of the substrate prior to imprinting. Such an arrangementis illustrated in FIG. 5. A portion of a substrate 50 is being patternedusing first and second templates 51, 52 which are moving anti-paralleland adjacent one another. Each template 51, 52 has an associateddispenser 53, 54 configured to dose a volume of imprintable medium 55,56 immediately in front of the template 51, 52 (i.e., on a targetportion of the substrate to be next imprinted) on a drop on demandbasis. The drop on demand dispenser may, for instance, be mounted tomove with the respective template.

FIG. 6 schematically shows a further embodiment of the invention.Portions of a substrate 60 are patterned using first and secondtemplates 61, 62 (the portions are delineated by dotted lines). Templateholders 63, 64 hold the imprint template 61, 62. The imprint templates61, 62 and template holders 63, 64 are moved parallel and adjacent toone another, as indicated by arrows A.

Each template 61, 62 has an associated plurality of dispensers 65-68.Those dispensers 66, 67, which are located in front of the imprinttemplates 61, 62 when they are moving in the direction indicated, areconfigured to dose volumes of imprintable medium (not illustrated) aheadof the imprint templates. This is done on a drop on demand basis. Thedispensers 66, 67 are fixed to the template holders 63, 64, and areseparated from the imprint templates 61, 62 by a certain distance. Thisallows a fixed timing to be set up between depositing the imprintablemedium and applying the imprint template to the imprintable medium sothat all the portions of the substrate have the same fixed timing. Thismay give very uniform processing conditions to all the portions on thesubstrate which may give better yield. By having the dispensers close tothe template the fixed timing between depositing the imprintable mediumand applying the imprint template to the imprintable medium may be bevery short which may be beneficial for throughput and may lower theamount of evaporation of the imprintable medium before applying of theimprint template to the imprintable medium.

In some instances in may be desired to move the imprint templates 61, 62in the x-direction (this includes the negative x-direction) prior toimprint. Where this is done dispensers 65, 68 provided at appropriatesides of the template holders 63, 64 may be used. It will be appreciatedthat dispensers may be provided on other sides of the template holders63, 64 if required or desired.

The dispensers 65-68 each comprise a plurality of apertures (these may,for example, be ink-jet nozzles) which are configured to dispense anarray of droplets of imprintable medium onto the substrate 60. Theplurality of apertures may, for example, be a two dimensional array, asshown in FIG. 6. The array of droplets of imprintable medium may, forexample, be arranged to correspond with the dimensions of the imprinttemplates 61, 62.

FIG. 7 schematically shows a further embodiment of the invention. Theembodiment shown in FIG. 7 corresponds in large part with that shown inFIG. 6, except that instead of each dispenser comprising an array ofapertures for dispensing imprintable medium, each dispenser 71-74comprises a single row of apertures. The apertures may, for example, beink jet nozzles. Where dispensers of this type are used, the imprintablemedium may be dispensed when the template holders 63, 64 are movingbetween imprint positions. This allows the imprintable medium to bedistributed across, for example, a portion of the substrate to beimprinted.

Although in some of the above described embodiments of the invention thedispensers have been referred to as being attached to template holders,it will be appreciated that the dispensers may in some instances beattached directly to imprint templates. In general, the dispensers areassociated with imprint templates, and may be said to be fixed relativeto imprint templates.

The throughput of the system may be improved or optimized by setting thetiming between depositing imprintable medium and imprinting for eachtemplate, such that imprinting occurs either in or out ofsynchronisation. An improvement in throughput of approximately 30-70%may be achieved for a two template system by arranging the imprintingand curing times appropriately.

In an embodiment, there is provided an imprinting method, comprising:providing first and second spaced target regions of a substrate withimprintable medium; contacting the first and second spaced targetregions with first and second templates respectively to form respectivefirst and second imprints in the medium; separating the first and secondtemplates from the imprinted medium; providing third and fourth spacedtarget regions of the substrate with imprintable medium; displacing thefirst template in a first direction from the first region to a thirdregion of the medium and displacing the second template in a seconddirection from the second region to a fourth region of the medium; andcontacting the third and fourth target regions with the first and secondtemplates respectively to form respective third and fourth imprints inthe medium.

In an embodiment, the method comprises providing separate first, second,third and fourth volumes of the imprintable medium on the substrate toprovide the spaced target regions of the medium. In an embodiment, thefirst direction is substantially parallel to the second direction. In anembodiment, the first and second templates contact the mediumsimultaneously. In an embodiment, the first and second templates contactthe medium sequentially.

In an embodiment, there is provided an imprinting apparatus, comprising:a substrate table configured to hold a substrate; a template supportconfigured to support first and second templates, the template supportconfigured to cause the first and second templates to contact first andsecond spaced target regions respectively of an imprintable medium onthe substrate to form respective first and second imprints in the mediumand to cause the first and second templates to separate from theimprinted medium; and a first dispenser configured to provide a firstvolume of the imprintable medium and a second dispenser configured toprovide a second volume of the imprintable medium, to provide the firstand second spaced target regions.

In an embodiment, the first and second dispensers are associated withthe first and second templates respectively. In an embodiment, the firstand second dispensers are fixed relative to the first and secondtemplates respectively. In an embodiment, the first and seconddispensers are provided with a plurality of apertures. In an embodiment,the plurality of apertures comprises a two-dimensional array ofapertures. In an embodiment, the plurality of apertures comprises asingle row of apertures. In an embodiment, the dispensers are configuredto provide separate third and fourth volumes of the imprintable mediumon the substrate to provide third and fourth spaced target regions. Inan embodiment, the template support is operable such that, afterseparating the first and second templates from the first and secondregions of the imprinted medium, the first template is displaced in afirst direction from the first region to the third region of the mediumand the second template is displaced in a second direction from thesecond region to the fourth region of the medium, and the templatesupport is operable to cause the third and fourth target regions to becontacted with the first and second templates respectively to formrespective third and fourth imprints in the medium. In an embodiment,the first direction is substantially parallel to the second direction.In an embodiment, the template support is operable so that the first andsecond templates contact the first and second regions of the mediumsimultaneously. In an embodiment, the template support is operable sothat the first and second templates contact the first and second regionsof the medium sequentially. In an embodiment, the template support isconfigured so that the first template is fixed relative to the secondtemplate. In an embodiment, the template support is configured so thatthe first template is moveable relative to the second template.

While specific embodiments of the invention have been described above,it will be appreciated that the invention may be practiced otherwisethan as described. The description is not intended to limit theinvention. For example, any number of templates having any appropriatesize and/or shape may be employed to suit a particular application.Furthermore, the speed at which the templates are moved around thesubstrate may be monitored and controlled to provide a good or optimalimprinting rate for a specific substrate size and pattern density.

1.-18. (canceled)
 19. An imprinting method, comprising: contacting eachtarget region of a first set of target regions of imprintable medium ona substrate with a first imprint template to form a first set ofrespective imprints at the first set of target regions; contacting eachtarget region of a second set of target regions of imprintable mediumwith a second imprint template to form a second set of respectiveimprints at the second set of target regions, the second set of targetregions spaced from the first set of target regions; and providingimprintable medium on the substrate during the time the first and/orsecond imprint template becomes from being located adjacent a firsttarget region to being located adjacent a second target region of therespective first and/or second sets of target regions.
 20. The method ofclaim 19, wherein the respective first and second imprint templatescontact a respective target region simultaneously.
 21. The method ofclaim 19, further comprising moving the first imprint template relativeto the second imprint template.
 22. The method of claim 19, comprisingproviding a first volume of imprintable medium to the first set oftarget regions and providing a second, separate volume of imprintablemedium to the second set of target regions.
 23. The method of claim 22,wherein providing the first and second volumes are associated with thefirst imprint template and the second imprint template respectively. 24.The method of claim 22, wherein providing the first and second volumesare at a fixed location relative to the first and second imprinttemplates respectively.
 25. An imprinting apparatus, comprising: asubstrate table configured to hold a substrate; a first imprint templatesupport configured to support a first imprint template, the firstimprint template support configured to cause the first imprint templateto contact each target region of a first set of target regions ofimprintable medium on the substrate to form a first set of imprints atthe first set of target regions; a second imprint template supportconfigured to support a second imprint template, the second imprinttemplate support configured to cause the second imprint template tocontact each target region of a second set of target regions ofimprintable medium to form a second set of imprints at the second set oftarget regions, the second set of target regions spaced from the firstset of target regions; and a dispenser configured to provide imprintablemedium on the substrate, while supported on the substrate table, duringthe time the first and/or second imprint templates becomes from beinglocated adjacent a first target region to being located adjacent asecond target region of the respective first and/or second sets oftarget regions.
 26. The apparatus of claim 25, wherein the first andsecond imprint template supports are operable so that the respectivefirst and second imprint templates contact a respective target regionsimultaneously.
 27. The apparatus of claim 25, wherein the dispensercomprises a first dispenser configured to provide a first volume ofimprintable medium and a second dispenser configured to provide asecond, separate volume of imprintable medium.
 28. The apparatus ofclaim 27, wherein the first and second dispensers are associated withthe first imprint template and the second imprint template respectively.29. The apparatus of claim 27, wherein the first and second dispensersare fixed relative to the first imprint template and the second imprinttemplate respectively.
 30. The apparatus of claim 25, wherein thedispenser comprises a first dispenser and a second different dispenser,the first dispenser configured to provide imprintable medium from afirst side of the first and second templates and the second dispenserconfigured to provide imprintable medium from a second different side ofthe first and second templates.
 31. The apparatus of claim 30, whereinthe first side is opposite the second side.
 32. The apparatus of claim25, wherein the dispenser is configured to provide separate volumes ofimprintable medium to the respective target regions.
 33. An imprintingapparatus, comprising: a plurality of independently movable imprinttemplate supports; and a plurality of imprintable medium dispensers. 34.The apparatus of claim 33, wherein each imprint template support has anassociated imprintable medium dispenser of the plurality of imprintablemedium dispensers.
 35. The apparatus of claim 33, wherein the pluralityof imprint template supports is configured for imprint templatessupported thereby to operate in parallel to each other.
 36. Animprinting apparatus comprising a plurality of imprint templatesupports, each configured to support an imprint template, wherein theplurality of imprint template supports is configured for the imprinttemplates to operate in parallel to each other.
 37. The apparatus ofclaim 36, further comprising a plurality of imprintable mediumdispensers, each imprint template support having an associatedimprintable medium dispenser of the plurality of imprintable mediumdispensers.
 38. The apparatus of claim 36, wherein the dispensers areconfigured to provide imprintable medium on a substrate during the timea first imprint template support and/or a second imprint templatesupport of the plurality of imprint template supports causes arespective first and/or second imprint template to contact a respectivetarget region.
 39. The apparatus of claim 36, wherein the dispensers areconfigured to provide imprintable medium on a substrate during the timea first imprint template support and/or a second imprint templatesupport of the plurality of imprint template supports becomes from beinglocated adjacent a first target region to being located adjacent asecond target region of respective sets of target regions imprintedusing the first imprint template support and/or the second imprinttemplate support.